/Engine/Plugins/Experimental/GeometryScripting/Source/GeometryScriptingCore/Public/GeometryScript/MeshQueryFunctions.h
Returns the number of topological boundary edges in the mesh, i.e counts edges that only have one adjacent triangle.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintPure, Category="GeometryScript|MeshQueries", Meta=(ScriptMethod)) static int32 GetNumOpenBorderEdges ( [UDynamicMesh](API\Runtime\GeometryFramework\UDynamicMesh) * TargetMesh )